ter Wee P M, van Ballegooie E, Rosman J B, Meijer S, Donker A J
Department of Nephrology, State University Hospital, Groningen, The Netherlands.
Nephrol Dial Transplant. 1987;2(6):504-9.
Glomerular hyperfiltration is one of the factors held responsible for the development of diabetic nephropathy. A supranormal glomerular filtration rate (GFR) can be found in diabetic patients even when they are well controlled. Infusion of low-dose dopamine demonstrates that glomerular hyperfiltration in well-controlled insulin-dependent diabetic patients is not based on a predominant vasodilatation of the efferent arteriole. In the present study this is confirmed, since the dopamine-induced rise in GFR of control subjects (13.5% +/- 2.2) did not differ from that of patients with insulin-dependent diabetes mellitus (10.8% +/- 2.1). In animal studies it has been demonstrated that the increased GFR in diabetes mellitus is caused by a predominant decrease in resistance of the afferent arteriole. Protein loading and infusion of amino acids also increase GFR by dilatation of the afferent arteriole. Thus, protein loading or amino acid infusion may be used to test the existence of afferent vasodilatation. The present study investigates the effect of amino acid infusion on GFR of control subjects and insulin-dependent diabetic subjects. The amino acid-induced rise in GFR tended to be lower in the diabetic patients (6.9% +/- 2.8) compared with controls (13.2% +/- 2.7). Percentage amino acid-induced change in GFR appeared to decline with increasing baseline GFR in the diabetic subjects (r = -0.83; P less than 0.001). In controls, no such relationship was established (r = -0.22; n.s.). Our results suggest the existence of afferent vasodilatation in diabetic patients with a high GFR. The cause of this vasodilatation warrants further study.
肾小球高滤过是导致糖尿病肾病发生的因素之一。即使糖尿病患者病情控制良好，也可发现其肾小球滤过率（GFR）超常。低剂量多巴胺输注表明，病情控制良好的胰岛素依赖型糖尿病患者的肾小球高滤过并非基于出球小动脉的主要血管舒张。在本研究中这一点得到了证实，因为多巴胺引起的对照组受试者GFR升高（13.5%±2.2）与胰岛素依赖型糖尿病患者的升高幅度（10.8%±2.1）并无差异。在动物研究中已表明，糖尿病时GFR升高是由入球小动脉阻力的主要降低所致。蛋白质负荷和氨基酸输注也通过入球小动脉扩张而增加GFR。因此，蛋白质负荷或氨基酸输注可用于检测入球小动脉扩张的存在。本研究调查了氨基酸输注对对照组受试者和胰岛素依赖型糖尿病受试者GFR的影响。与对照组（13.2%±2.7）相比，糖尿病患者中氨基酸引起的GFR升高趋势较低（6.9%±2.8）。在糖尿病受试者中，氨基酸引起的GFR变化百分比似乎随着基线GFR的升高而下降（r = -0.83；P<0.001）。在对照组中，未建立这种关系（r = -0.22；无显著性差异）。我们的结果提示，GFR高的糖尿病患者存在入球小动脉扩张。这种血管舒张的原因值得进一步研究。
